The Modular Connector and How It Got That Way

They adorn the ends of Cat5 network patch cables and the flat satin cables that come with all-in-one printers that we generally either toss in the scrap bin or throw away altogether. The blocky rectangular plugs, molded of clear plastic and holding gold-plated contacts, are known broadly as modular connectors. They and their socket counterparts have become ubiquitous components of the connected world over the last half-century or so, and unsurprisingly they had their start where so many other innovations began: from the need to manage the growth of the telephone network and reduce costs. Here’s how the modular connector got that way.

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MIDI Association Releases Spec For TRS Jacks

The MIDI spec was released in 1983, and for more than thirty years every synthesizer, drum machine, and piece of computer hardware with MIDI has sported an enormous DIN-5 jack on the back. Why did they choose such a large connector? Well, MiniDIN connectors hadn’t even been invented yet, and today even MiniDIN connectors are rarely-seen, obsolete connectors.

In the last decade, MIDI has found its way into some very small machines. Those Pocket Operators have MIDI sync, you can control a Game Boy with MIDI using the right hardware, and the cute little Korg synths also have MIDI tucked away in there somewhere. You can’t put a DIN-5 jack on those things, leading to some weird implementations of MIDI over non-standard connectors.

Now the MIDI Association has weighed in on the situation. There’s now a spec for MIDI over 2.5mm and 3.5mm TRS jacks. In just a few short decades, you’ll be able to connect MIDI gear with an audio aux cable.

Although there are five connectors in a DIN-5 jack, most implementations use only two connectors to send and receive data. Synth manufacturers have capitalized on this fact and cheap TRS connectors to build their own implementation of MIDI using smaller connectors, sometimes with incompatable pinouts.

Now, though, there’s a standard. For TRS connectors, the tip is pin 5 on the DIN-5, the ring is pin 4, and the sleeve is pin 2. It sends and receives data to synths and drum machines from 1983, and it doesn’t use gigantic connectors.

The only caveats to the new MIDI standard is that 2.5mm TRS connectors are recommended, and that protection circuitry is strongly recommended in the case a headphone driver is inevitably connected to a MIDI device. Other than that, everything’s coming up roses, and this opens up the door to MIDI jacks that are much, much easier to source.

The Electrical Outlet and How It Got That Way

Right now, if you happen to be in Noth America, chances are pretty good that there’s at least one little face staring at you. Look around and you’ll spy it, probably about 15 inches up from the floor on a nearby wall. It’s the ubiquitous wall outlet, with three holes arranged in a way that can’t help but stimulate the facial recognition firmware of our mammalian brain.

No matter where you go you’ll find those outlets and similar ones, all engineered for specific tasks. But why do they look the way they do? And what’s going on electrically and mechanically behind that familiar plastic face? It’s a topic we’ve touched on before with Jenny List’s take on international mains standards. Now it’s time to take a look inside the common North American wall socket, and how it got that way.

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Converting Power Supplies for Antique Computers

Just because something is “never used” doesn’t mean it’s good. [Inkoo Vintage Computing] learned that lesson while trying to repair an Amiga 500 and finding parts online that were claimed to be “new” in that they were old stock that had never been used. The problem was that in the last 30 years the capacitors had dried out, rendering these parts essentially worthless. The solution, though, was to adapt a modern PSU for use on the old equipment.

The first hurdle to getting this machine running again was finding the connector for the power supply. The parts seemed to have vanished, with some people making their own from scratch. But after considering the problem for a minute longer they realized that another Commodore machine used the same parts, and were able to source a proper cable.

Many more parts had to be sourced to get the power supply operational, but these were not as hard to come across. After some dedicated work with the soldering iron, the power supply was put to use running the old Amiga. Asture readers will know that [Inkoo Vintage Computing] aren’t strangers to the Amiga. They recently were featured with a nondestructive memory module hack that suffered from the same parts sourcing issues that this modification had, but also came out wonderfully in the end.

JST Is Not A Connector

When reading about cool projects and products, it’s common to see wiring plugs labelled “JST connector.” This looks fine until we start getting hands-on and begin hacking things together. Inevitably we find the JST connector from one part fails to fit in the JST connector of another. This is the moment we learn “JST” is not a connector specification. It is short for Japan Solderless Terminals Manufacturing Company, Ltd. A company whose history goes back to 1957 and their website (styled in 1999) lists hundreds of different types.

We can simplify to “JST connector” when chit-chatting about projects. But when it comes to actual hardware specification, that’s not good enough. Which JST connector?

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Magsafe 1 to Magsafe 2 The Cheap Way

[Klakinoumi] wanted to use their Magsafe 1 charger from 2007 with their newer Macbook Pro Retina from 2012 — but it had a Magsafe 2 port. There were a few options on the table (buy an adapter, buy a new charger, cry) but those wouldn’t do. [Klakinoumi] went with the brute force option of grinding a Magsafe 1 charger to fit Magsafe 2.

Based on the existence of passive adapters that allow Magsafe 1 chargers to work with newer laptops, we’d assume that the older chargers are probably electrically similar to the newer models. That said, it’s not our gear and we’d definitely be checking first.

With that out of the way, it’s a simple enough modification — grind away the Magsafe 1’s magnet until it fits into a Magsafe 2 port. It really is that easy. The spring-loaded pins all seem to line up with the newer port’s pads. [Klakinoumi] reports it worked successfully in their tests with 2012, 2014 and 2015 Macbooks but that it should be attempted at your own risk — good advice, as laptops ain’t cheap.

When doing this mod, consider taking care not to overheat the connector during grinding. You could both melt plastic parts of the connector, or ruin the magnet by heating it past its Curie point.

Interested in the protocol Magsafe speaks over those little golden pins? Find out here.

Good in a Pinch: The Physics of Crimped Connections

I had a friend who was an electronics assembly tech for a big defense contractor. He was a production floor guy who had a chip on his shoulder for the engineers with their fancy book-learnin’ who couldn’t figure out the simplest problems. He claimed that one assembly wasn’t passing QC and a bunch of the guys in ties couldn’t figure it out. He sidled up to assess the situation and delivered his two-word diagnosis: “Bad crimp.” The dodgy connector was re-worked and the assembly passed, much to the chagrin of the guys in the short-sleeved shirts.

Aside from the object lesson in experience sometimes trumping education, I always wondered about that “bad crimp” proclamation. What could go wrong with a crimp to so subtly futz with a circuit that engineers were baffled? How is it that we can rely on such a simple technology to wire up so much of the modern world? What exactly is going on inside a crimped connection anyway?

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